Another day, another chapter in the ongoing escalation of tensions between the US and North Korea.

On Sunday, US President Donald Trump tweeted that he had told Secretary of State Rex Tillerson he was “wasting his time” in pursuing negotiations between the two nations, telling him “we’ll do what has to be done”.

I told Rex Tillerson, our wonderful Secretary of State, that he is wasting his time trying to negotiate with Little Rocket Man...

Trump’s brief statement on Twitter came just a day after Tillerson announced the US is maintaining direct channels of communications with North Korea on a trip to China.

“We have lines of communications to Pyongyang,” Tillerson said. “We’re not in a dark situation, a blackout.

“We have a couple… three channels open to Pyongyang. We can talk to them, we do talk to them.”

Exchanges between the two nations have grown increasingly tense in recent months as North Korea continues to test long-range missiles potentially capable of carrying nuclear payloads.

China US Tillerson

Name-calling has become part of the rhetoric from both sides, with Kim Jong Un declaring Trump a mentally deranged “dotard” in response to Trump calling him “rocket man”, both on Twitter and during a speech to the UN.

Trump once again used this moniker to describe the North Korean leader in his tweet to Tillerson on Sunday.

The White House is yet to clarify exactly what Trump meant when telling Tillerson that the US government will “do what has to be done”.